Jack usually mows his lawn in 6 hours. Marilyn can mow the same yard in 4 hours. How much time would it take for them to mow the lawn together?

Question

anonymous · Answer

2 hrs

amistre64 · Answer

the idea is to determine how much work each one does in 1 "hour" as this case is

amistre64 · Answer

J can do it all in 6 hours; how much can he do in 1 hour?  1/6 of it right?

amistre64 · Answer

M can do it all in 4 hours, which means that in 1 hour she does 1/4 of it

amistre64 · Answer

together in an hour they can do:

1/6 + 1/4 = (6+4)/24 = 10/24

amistre64 · Answer

this tells us we divvy the yard up into 24 pieces and see how long it takes them to finish it all

10 * t = 24

t = 24/10 = 2.4 hours

amistre64 · Answer

if I was british, I could convert that into minutes